The invention concerns a wound tube made of profiled plastic strips whose edge regions are designed such that when winding contiguous edge regions of the plastic strip of two successive windings [said windings] can be connected in a form-fitting manner and in which at least one of the surfaces of the plastic strip has ribs that essentially project orthogonally and are equally spaced.
Wound tubes made of plastic strips are used in the restoration of waste water channels and are produced on site. In a process disclosed in EP 2 085 29 A1, DE 696 27 426 T2 or DE 696 35 214 T2 the tube is made in the waste water channel whereby the assembler moves through the waste water channel as the production progresses and makes the wound tube from a profiled plastic strip that is guided through its assembler portion. In a different process that is disclosed in EP 0 023 242 or EP 0 109 413 the assembler is stationary in a revision shaft of the waste water channel that is to be restored and the profiled plastic strip is provided via the revision shaft. The wound tube that is made by the assembler is inserted into the channel as it is finished. The plastic strips used for making such wound tubes comprise a groove extending longitudinally along an edge side and a bead extending longitudinally along the other edge side so that the bead of the one edge region fits into the groove of the subsequent edge region in a form-fitting manner during winding. This form-fitting results in a tight connection which can be improved using additional means, for example cold welding.
In such wound tubes poor stability, at least in large diameter tubes, is a disadvantage. By including radially projecting ribs on the outer surface of the plastic strip forming the outer wall, stability can be increased, however, here, too, the diameter for stable wound tubes is limited. To compensate for this insufficiency and to provide sufficient stability, the hollow spaces that necessarily remain between the wall of the waste water channel and the wall of the wound tube in these manufacturing processes must be filled.
It is desirable to provide a wound tube with increased stability that can easily and inexpensively be produced with profiled plastic strips on site for the restoration of waste water channels and can be introduced into the channel to be restored without any complete filling; furthermore a device is to be provided with which such wound tubes can advantageously be produced on site.
In wound tubes according to an aspect of the invention, the tube walls are double walls. To this end a first, inner plastic strip and a second outer plastic strip are joined so that the two plastic strips are at a radial distance from one another. Essentially orthogonally projecting ribs of the two joined plastic strips are arranged radially and opposite one another for support purposes. The arrangement is such that the edge region of the one plastic strip is offset by at least one rib distance in axial direction in relation to the edge region of the other plastic strip. By offsetting the edge region of the inner plastic strip in relation to the edge region of the outer plastic strip, joining them automatically is facilitated. The plastic strip forming the outer wall advantageously also has ribs projecting on the outside, which significantly increases the stability of the resulting wound tube. Such plastic strips can easily be produced using extrusion.
In an advantageous further development at least some of the ribs, preferably all of them, of one of the plastic strips are reinforcement ribs with a rib head. The ribs of the other plastic strip corresponding to these ribs comprise a head receptacle that can accommodate the respective rib heads. After the two plastic strips are joined to form the double wall band, the respective rib heads are inside the respective head receptacles—in this manner the inner and outer plastic strips are joined in a form-fitting manner.
It further is advantageous for both plastic strips to comprise reinforcement ribs with rib heads and ribs with head receptacle. They are arranged alternately so that both identically designed plastic strips can be joined to form the plastic band by joining the ribs that face each other. After the two plastic strips are joined, the respective rib heads are located in the respective head receptacles in a form-fitting manner. This means production is restricted to one plastic band with a uniform cross-section and only spools of identical plastic strips with a uniform cross-section are required on site.
This connection is locked into position. To this end the engaging rib heads are designed as a kind of harpoon head and the head receptacles are designed accordingly so that when the outer plastic strip and the inner plastic strip are joined, they slide into place and automatically secure the connection. To make this permanent, it is possible to glue or weld the connection. To this end at least some of the rib heads and/or head receptacles contain glue or an agent that results in cold welding and thus can be glued or welded together.
When producing the wound tube, the two plastic strips are joined to form a double strip and are bent around a bend radius that corresponds to the diameter of the tube to be inserted into the channel that is to be restored. This results in a difference in length between the outer plastic strip and the inner plastic strip. To compensate for this difference in length, at least one of the plastic strips comprises means for compensating for the length. To this end it is advantageous to have U-shaped or OMEGA-shaped elbows between two reinforcement ribs or between two ribs.
To secure the connection of the edges, a counter bracket with latch head receptacle is provided in one edge region of the plastic strips while the other edge region of the second plastic strip comprises a retaining rib with a retaining rib head. This retaining rib head is designed such that it is inserted into the latch head receptacle of the counter bracket and latches when the edge regions of the two plastic strips of two adjacent windings of the wound tube are joined. It further is advantageous when a locking rib is molded at an obtuse angle to the edge region of one of the plastic strips. When the edge regions of the two plastic strips are joined, said locking rib rests against and blocks the outermost reinforcement rib. It is understood that in order to maintain the uniform cross-section, one of the edge regions of the plastic band must comprise counter brackets with latch head receptacles and the other edge region must comprise retaining ribs with retaining rib heads and one edge region comprises a locking rib arranged at an obtuse angle.
A suitable device for producing such wound tubes is a set of rollers that is arranged in the area of the mouth of the channel that is to be restored said set of rollers forming the winding for the wound tube. However, it comprises a roller advance for joining the two plastic strips to form the double band required for the wound tube so that the joined double band is fed to the set of rollers for forming the winding.
It is advantageous when the roller set is preceded by a device with which glue or an agent for cold welding the engaging ribs of the plastic strips and/or the engaging edge regions of the plastic strip can be applied. These means secure the per se solid latching of the joined plastic strips.
When applying the glue or the agent for cold welding in the glue application device, the application occurs with a roller. To this end an application roller runs through a glue reservoir and takes up glue when it resurfaces. Then the glue or the agent for cold welding that was taken up is transferred to the respective areas of the plastic strip whereby pressure rollers ensure that the application is carried out properly. A different process would be a spray on process whereby areas of the plastic strip that do not need to be sprayed are covered in the spray area. In both cases it is possible to arrange wipe off devices that remove any excess glue. For certain types of glue joining must occur immediately after the glue is applied. In this case the glue application device is arranged directly in front of the rollers that join the two plastic strips. If the glue must dry for a certain period of time, the time period can be adjusted by selecting the corresponding distance between the glue application device and the rollers that join the two plastic strips and taking the respective feed rate into account. An application with other means, such as spray cans, is possible as well.
The plastic strips are removed from the storage spools that are above ground and are fed to the on-site winding assembler through the revision shaft. In doing so, the surface of the plastic strips can pick up dirt, which can impede the latching of the ribs and the edge regions. To avoid this problem and to protect the plastic strips that are removed from the storage spools and fed to the winding assembler with intake roller set through the revision shaft, means for protecting the profile are arranged in the revision shaft that surround both plastic strips and thus protect them against dirt in particular. In case of deep channels the suspended load of the plastic strips that are fed to the winding assembler through the revision shaft can become so high that it might affect the feed process. In such cases it is advantageous to include additional brake rollers that take up at least part of the load. Said brake rollers advantageously are arranged in the protection guide.